Pittsburgh Police Officer Kevin Merkel salutes as he stands with his K-9 partner Tonky during a memorial service for Port Authority of Allegheny County K-9 Officer Aren at the Allegheny County Law Enforcement Officer's Memorial on the North Side on Thursday, Feb. 4, 2016.  Officer Aren, the five-year-old German shepherd was killed Sunday after being stabbed during an attempted arrest in Wilkinsburg.